Australia's NW coast is one of the most sparsely populated places on earth but contains vast oil and gas reserves which are being rapidly developed. The region is subject to severe oceanographic conditions including waves and currents from frequent tropical cyclones and large internal waves, creating problems when developing or operating offshore facilities. Waves and currents from cyclones control the maximum loads expected at a platform in its lifetime and gaining an insight into the likely magnitudes of these is a key part of developing safe structures. Using a MIKE 3, 60 layer, non-hydrostatic model, Woodside Petroleum’s Metocean group has modelled the currents produced under combined cyclone and internal wave activity out to the 10,000 yr Return Period.

Excellent comparisons between measured and modelled current speeds under severe Hurrricanes Ivan and Rita in the Gulf of Mexico as well as under 5 severe tropical cyclones affecting NW Australia has been achieved. The model has also been tested against other industry-standard systems and proven to be the most accurate and robust tool for the job.

The first animation shows, in the upper panel, a 2-D spatial map of modeled surface current during a typical spring tide and, in the lower panel, a concurrent cross section of the same parameter, demonstrating the model’s ability to capture internal wave formation, shoaling and dissipation across the shelf.

The second animation shows the same thing but this time with severe Tropical Cyclone Vance (1999) passing overhead.